A growing body of evidence suggests that inadequate incorporation of docosahexaenoic acid (DHA) in brain during development affects the CNS dopamine systems and, when combined with appropriate genetic and/or other epigenetic factors, contribute to the risk of developing ADHD or to the severity of the disease. This proposal addresses the HYPOTHESIS that low brain DHA levels during early development alter dopaminergic function producing hyperactivity and attentional deficits similar to the symptoms of ADHD. The OBJECTIVE of this study is to assess the behavioral and neurochemical effects of clinically-relevant variation in brain DHA content during early development. The Specific Aims will use a rat model to determine: [unreadable] [unreadable] 1. The effects of low brain DHA content during early development on activity and attentional processes in the developing rat. A force-plate actometer will be used to measure simultaneously assess activity and attentional processes in rats raised from conception on diets designed to modulate brain DHA content. [unreadable] [unreadable] 2. The effects of methylphenidate on hyperactivity and attentional processes in juvenile rats with low brain DHA content during early development. Dose-response effects of this drug used in the treatment of ADHD will be determined using the force-plate actometer. [unreadable] [unreadable] 3. The effects of low brain DHA content during early development on dopaminergic neurochemistry in juvenile rats. Dopamine content and turnover and the density of dopamine receptors and transporters will be assessed in specific brain regions. [unreadable] [unreadable] 4. The critical developmental period(s) when sufficient brain DHA content is essential for normal development of the dopamine systems. Treatment with DHA will be initiated at various time points between birth and weaning to determine when neuroplasticity is present. [unreadable] [unreadable] These experiments will show the relationship between brain DHA content and dopaminergic functioning and behavioral indices of hyperactivity and attentional processes. These findings will provide timely and important insights into mechanisms of brain development and perinatal nutrition and provide insights into the etiology of ADHD in humans. Such insights may identify a means by which certain risk factors for ADHD may be reduced or eliminated or the severity of the disease may be reduced through appropriate pre- and postnatal nutrition. [unreadable] [unreadable]